The purpose of this study was to clarify the principal factors related to shot situations that affect the outcome of goalkeeping saves in soccer and to build a regression formula that would predict the difficulty of saving a shot. The samples were 551 shots at goal in the 2010 FIFA World Cup in South Africa. The shots data were collected using game performance analysis. For statistical processing, the principal factors affecting the outcome of a save in soccer were revealed using logistic regression analysis. The principal factors that influenced the results of a save attempt were: the duration between initiation of the shot and when the ball reached the goal, the presence or absence of a defender in front of the shooter, the presence or absence of a defender located lateral or posterior to the shooter, the part of the body used to perform the shot, i.e. the head or the leg, the type of shot, i.e., a liner, a lob, or a grounder, the shot course in a mediolateral direction, the shot course in a vertical direction, the presence or absence of a change in the direction of the shot by other players, the shooter's position angle in relation to the goal line and the line from the goal post to the shooter, and the distance from the center of the goal to the ball when the ball reached the goal line. In addition, a regression formula was constructed to predict the difficulty of the save by combining the odds ratios of the main factors. It was verified that the difficulty in making a save could be accurately predicted using the regression formula (84.8%). As a future task, using our regression formula, it would be practically important to develop predictors for evaluating the ability of a goalkeeper.

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The present study was verify of reliability and validity the regression equation constructed using the game footage from the 2010 FIFA World Cup. Formulated using multivariate logistic regression analysis, this equation’s purpose was to predict the probability of a goalkeeper’s failure to stop shots at goal. The 2014 dataset consisted of 587 shots at goal from within the frames during 64 games played by 32 teams that participated in the FIFA World Cup in Brazil. The results showed that for the probability of failing to block a shot predicted by the regression equation, the 2 inter-rater interclass correlation coefficient was high (0.91), thus demonstrating reliability. Furthermore, when a contingency table was created with a cut-off value of 0.5, accuracy was high (85.9%); when an ROC curve was drawn and the area below the curve was measured (0.874), it was notably distinct, indicating generalizability. Therefore, the regression equation predicting the probability of failure to block a shot has high generalizability for predicting world-class goalkeepers’ probability of failure to block shots. This is considered a useful formula for evaluating goalkeepers’ blocking ability.

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